Lessons learned from Summer 2025 for Europe’s airports

By Pieter Callewaert, Aircraft Flow Process Manager at Brussels Airport Company, ACI EUROPE’s Director of Airport Capacity & Operations, Aidan Flanagan, and Jeffrey Schäfer, Process Owner Aircraft Turnaround at Royal Schiphol Group.

While you may be reading this with thoughts of snow and the holiday season on your mind, it is still never too late to look back on how European airports and aviation performed in Summer 2025. The Summer 2025 season and what it demonstrated have substantial implications for airport performance throughout the rest of the year and beyond, offering key strategic insights.

Let’s start on a positive note: Summer 2025 delivered some of the most encouraging operational results Europe has seen in several years. In terms of flight movements, traffic grew by 3% and reached a record week in late August; arrival punctuality climbed to 71%; and total ATFM delays fell by more than a quarter compared with the previous year. These results are a marked improvement on Summer 2024 and demonstrate the results of the collaborative efforts between stakeholders coordinated by the Network Manager (EUROCONTROL).

But Summer 2025 also exposed the fragility of these gains. Delays remain above European targets, structural capacity constraints persist, particularly around key Area Control Centres (ACCs), and the system continues to rely heavily on favourable weather and daily tactical interventions to remain stable. Had it not been for better weather –always a marker of a good summer holiday – and conservative assumptions in airline scheduling, this summer could have been more like the last. Airports, standing at the nexus of the passenger experience and the operational realities of the network, witnessed both the progress and the persistent vulnerabilities firsthand.

However, EUROCONTROL data confirms that Summer 2025 was operationally stronger across almost every Key Performance Indicator. Average daily traffic reached 35,122 flights (+3% vs 2024 and +1% vs 2019), with the busiest week ever recorded (Week 35) and the busiest Saturday and Sunday (9 and 10 August) in network history. In terms of passengers, movement was similar, with a 3.3% increase on 2024 across June-September¹.

Despite higher traffic, ATFM delays fell from 5.4 to 3.9 minutes per flight (-27% vs 2024). En-route delays dropped significantly (-34%), supported by a 43% reduction in weather-related delay and a 22% improvement in staffing-related delay. Weather-avoidance coordination alone saved an estimated 720,000 minutes of delay across the season.

These improvements reflected:

• consistent use of the Network Operations Plan,
• stronger cross-border weather procedures,
• close daily coordination between EUROCONTROL (Network Manager) and operational actors, and
• more realistic first-rotation planning.

Nonetheless, delay hotspots persisted. France, Spain and Germany accounted for over half of all en-route delays, with France representing 31% of all en-route delays. Structural ATCO shortages, limited airspace availability (not least due to Ukraine-related constraints), and convective weather continued to drive volatility at the network level.

From an airport perspective, Summer 2025 once again demonstrated both the strengths and the limits of the current European performance model. While the narrative and coordination among stakeholders focus on the summer period, the issues presented by summer are chronic year-round concerns that are drawn into sharpest relief at the time of highest demand and stress on the Network.

These challenges do not disappear along with the last parasols and beach balls, nor with a fortunate spell of good weather. If anything, the better weather this summer clarified the performance picture and better demonstrated the structural problems which necessitate a strategic shift in mindset.

Airports delivered smoother operations, stronger on-time performance, and improved passenger flow this summer. But they also faced persistent challenges tied to factors outside their control, and which are not unique to the June-September period:

• flights arriving too early or too late, which disrupts stand allocation, gate planning and passenger flows,
•  the planning of different operational stakeholders (e.g. ground handlers), causing capacity/resource issues on their side, which potentially creates even more delays,
• upstream en-route delays creating rotation pressure,
• schedule-quality issues leading to unrealistic, unachievable turnarounds.

Furthermore, while arriving early is often portrayed by airlines and perceived by passengers as a good thing, in reality, it causes all manner of complications for the airport and operational stakeholders on the ground, who expect an aircraft at a particular time to maintain their intricate, well-planned schedule. Aircraft may have to wait on the taxiway/apron until their stand becomes available at the forecast arrival time, or ground handling staff may initially be diverted from servicing other flights to work on an early-arriving one. ATC may end up penalising already-late flights to make way for those ahead of schedule. At the same time, passengers may find themselves waiting in border queues or at baggage reclaim because resources were initially planned around the airline’s provided schedule.

For these reasons, airports have consistently argued that network performance is inseparable from airport performance, and that the conversation must shift from measuring outcomes to managing the operational inputs that drive them. In other words, we must move from viewing success solely in terms of the minimal delay possible for flights to a more holistic view of how on-time a flight – and its passengers – are.

This is precisely the shift advocated in ACI EUROPE’s new Airport Performance Position Paper, released at Airports Innovate in Busan. The paper calls for a fundamental repositioning of capacity and performance management: from reactive measurement to proactive, predictive control, with airports empowered to manage the operational inputs that determine performance outcomes.

Today’s performance framework focuses on results: delays, on-time performance, and reactionary knock-on effects. Airports argue that these indicators describe performance, but do not shape it. ACI EUROPE proposes a shift towards leading indicators such as:

• gate and stand allocation quality,
• asset readiness and availability,
• turnaround process reliability,
• resource planning and staffing predictability,
• robustness of operational data-sharing.

These inputs are what generate punctuality, resilience, and predictability for passengers.

Airports sit at the centre of a complex ecosystem of ground handlers, airlines, ANSPs, security providers and regulators. They are uniquely positioned to orchestrate system-wide performance, not by taking over other actors’ roles, but by providing the shared situational awareness supported by operational data and a collaborative decision-making framework needed for stable operations. This places airports in their natural role as masters of their Performance.

Additionally, physical capacity expansion in Europe is increasingly constrained by regulatory, financial, and environmental realities. This means that airports cannot simply build their way out of capacity pressures. They must be empowered to operate smarter, with more and stronger data, more transparency, and a clearer leadership role in performance management. Even where capacity expansion is possible, the same goals apply, enabling capacity and performance optimisation, as well as managing traffic growth resulting from expansion.

Just as you may book your escape to the beach while languishing in the depths of winter, the aviation ecosystem has already begun making preparations for Summer 2026. Such preparations focus on structural improvements:

• harmonised network weather and capacity procedures,
• improved rostering and accelerated ATCO recruitment,
• airspace design changes and sectorisation updates,
• digitalisation, datalink expansion and system modernisation.

It is imperative, though, that this work be seen not as an act of applying a lick of paint in time for the next wave of holiday-makers, but rather as laying the foundations of sustained, structural reform of performance.

Against this backdrop, ACI EUROPE’s strategy and advocacy highlight what is needed to translate Summer 2025’s gains into sustained performance:

• Aligning the network around airport-led predictability

Predictability at airports – on the stand, during the turnaround, and in the passenger flow – is the foundation of predictable network performance. This requires schedule realism, operational discipline, and consistent application of collaborative processes.

• Embedding the AOP across the European network

A standardised, collaboratively agreed AOP – linked digitally with the NOP – is essential to anticipate disruption, balance demand and capacity, and maintain flow resilience.

• Recognising airports as strategic performance leaders

Running an airport is often like managing a factory you have invested in, without really being able to control its throughput. That must change through regulatory and structural updates: most urgently, a revision of EU airport slot rules to ensure transparency, efficiency and integrity in how capacity is used and protected.

Airlines, ANSPs, ground handlers, the Network Manager and airports must all commit to the same standards of predictability, staffing readiness, and data accuracy and quality. Only then can Europe shift from a reactive summer-crisis mindset to a stable, predictable, passenger-centred performance model.

Summer 2025 showed that Europe’s aviation system can perform when collaboration, planning discipline and data-driven coordination come together. But it also revealed that the system is still too dependent on favourable circumstances and not yet equipped with the structural, regulatory and technological foundations needed for sustained, year-round resilience.

Airports are ready to lead a new era of performance management, centred on predictability, collaboration and the passenger. To succeed, they must be supported with a framework that recognises their central role in Europe’s aviation ecosystem.

¹ ACI EUROPE data